Is UT just a little too high-end for your
look-I'm-using-my-15-year-old-P100-as-a-Linux-box machine?

If so, you may be interested in either the original TTYQuake,
or you can do the exact same as above with many many
SDL-based games, or, if you're determined to be obscure,
AAQuake2
utilises a dedicated AALib renderer as opposed to merely utilising
SDL, as I did.